Keys with mechanical and non-mechanical closing and opening codes have formed the subject of considerable research since the appearance of electronic means, whose size is much smaller than that of valve technology-based means. However, the factual compulsions inherent in this problem are so diametrically opposed that the unavoidable compromises involved have led to solutions which generally lead away, or are even forced away from the sought objective.
For example, there are non-electronic keys which influence electronic scanning means, said keys generally being made from metal, a magnetomechanical device making such keys electronically readable. For example, such keys have a round bit profile, whose periphery houses magnetic portions or at least portions with alternating permeability, so that such keys can be electronically sensed by a rotary closing movement. Examples thereof are described in DOS Nos. 3,205,586 and 3,245,681, but these are neither flat nor electronic keys.
Thus, e.g. DE-OS No. 3,245,681 discloses a key with combined mechanical and non-mechanical, magnetic coding, said non-mechanical coding being in the form of an annular data medium. The inventor of the key described therein refers to DE-AS No. 2,325,566, which describes a flat key with non-mechanical and mechanical coding. However, this specification does not clearly state how said coding is obtained and how it is realisable. However, the reference to the fact that the magnetic key "secret" appears on the back of the key awakens the impression that it is a question of possible magnetic embedded portions distributed over the key bit length. Alternatively, it may not be a real code, but only a magnetic point on the key back which, in the correct position under the reader, releases the electrical locking system. However, the inventor of DE-OS No. 3,245,681 considers it disadvantageous to equip a flat key with non-mechanical codes, particularly because comparatively speaking only few code variants are possible. Thus, a flat key has little space for housing other than the mechanical codes provided. This is mainly due to the fact that flat keys are generally products of key miniaturization from which everything causing physical enlargement has been removed. In addition, such flat keys have become standard in their field and are still being used in increasing numbers. The factual compulsion of still incorporating further elements into a key having an optimized configuration fails due to the result of efforts lasting over many decades, namely of housing the maximum mechanical coding in the limited space of an elegant, flat key, which fits well into the pocket.
Thus, in order to achieve results in the combination of mechanical and electrical coding possibilities on the same key, it is e.g. on the one hand necessary to leave the flat key shape, as is done in DE-OS No. 3,245,681, where it is indicated as being essential to the invention, or on the other hand the mechanical coding is completely eliminated and replaced by a complicated electronic equipment, which simultaneously leads to a new key shape, so that the thus shaped keys can no longer be used in conjunction with existing standard combination locks.
Such an electronic solution is disclosed by U.S. Pat. No. 4,297,569, which describes a purely electronic "key" without mechanical coding, in which in key-like form, plastic is injected around an integrated circuit. This key has no mechanical coding and is not really a key in the conventional sense, it merely having a shape similar to a key. As stated, it comprises a DIL (dual in-line) semiconductor chip with plastic injected round it and with twice eight contact banks, the latter being used as "key contacts". The chip is embedded in the bit and the grip is developed to such an extent that the key can be correctly manipulated by the average size hand. However, the dimensions of this key are far removed from the standard dimensions of a flat key, it having the thickness required by the injection moulding of a commercially available DIL chip. The electronic key is also given its necessary stability by this thickness.